New Nanotech Helps Detect Early-Stage Cancer 18
CWmike writes "Stanford University researchers have used nanotechnology and magnetics to create a biosensor that they said should be able to detect cancer in its early stages. The sensor, which sits on a microchip, is 1,000 times more sensitive than cancer detectors used clinically today, say scientists at Stanford. The researchers announced this week that the sensors have been effective in finding early-stage tumors in mice, giving them hope that it can be equally successful in detecting elusive cancers in humans. 'In the early stage [of a cancer], the protein biomarker level in blood is very, very low, so you need ultra-sensitive technology to detect it,' said Shan Wang, professor of materials science and engineering at Stanford. 'If you can detect it early, you can have early intervention and you have a much better chance to cure that person.' Wang also noted that the biosensor could be used to determine whether chemotherapy or other cancer treatments are working after only a few days."
For anyone interested in a real description... (Score:5, Informative)
Essentially they're using magnetic nanoparticles covered with antibodies to detect the binding of some tumor biomarkers. While the idea is interesting, there's no indication (yet) that its more sensitive than other biomarker assays, although it very well may be. Fluorescence techniques can get down to the tens of molecules level of sensitivity (which is insanely impressive). If they can get even lower, I'd be extremely impressed, but I can't find any published data on their immunoassays. Their comments about capturing and sorting out cancer cells is a bit odd. If you're looking to isolate whole cells based on recognizing protein biomarkers, I can't see any advantages of their tech over standard fluorescence activated cell sorting (FACS), unless their assays are really more sensitive.
Really, the only thing of interest in this work is using the magnetic properties of their nanoparticles to detect binding. I would be really curious to see if this could supplant technologies like quartz crystal microbalances that look for changes in the vibrational modes of a crystal to detect surface binding events as being simpler and less prone to disruption by temperature fluctuations, doors opening or people walking by. The biomarker assay is interesting but by no means genuinely new technology- only the detection method is truly novel. Not bashing the work done here, the binding assay is really cool, the application looks like it was mostly thought of to get grant money.
Re:For anyone interested in a real description... (Score:5, Informative)
After reading some of the Stanford press out there on this, I've gotta say I'm really sick of 'science' journalists. Saying their test can detect cancer with 1,000 times the sensitivity and specificity has very different meanings than what they intended in diagnostics. It sounds like they're claiming 1,000-fold improvements in false negative (sensitivity) and false positive (specificity) rather than assay sensitivity based on concentrations. Their claim is also inaccurate. ELISA assays are commercially available with sensitivities as high as 1 part per 10 billion, while their claim is for a sensitivity of 1 part per 100 billion. ELISA assays have also been reported (and a couple are commercially available) with sensitivities of 1 part per 100 billion.
What "protein biomarker" are they talking about? (Score:2, Informative)
Cancer can affect the levels of various proteins in the blood: prostate cancer can raise prostate specific antigen, carcinoembryonic antigen is associated with colon and other cancers, alpha-fetoprotein is associated with liver and other cancers... the list goes on and on.
The problem is that these proteins are produced by normal cells but cancer cells often produce them in excess. The ability to detect these proteins has never been a problem. The problem is that they often only reach a very high level when the cancer has spread. The only protein used in cancer screening is prostate specific antigen and the benefit of this test is very contentious as its use has resulted in many a false negative and false positive diagnosis.
A real discovery would be to identify a blood marker that is useful for screening. It must be sensitive enough to enable detection while the cancer is curable but still maintain a very low false positive rate - as of today this doesn't exist for any cancer.
Publication is here: doi:10.1038/nm.2032 (Score:3, Informative)
I'm part of this research and I'm pleasantly surprised someone posted it on Slashdot. To answer some questions: The device is indeed a concentration-measuring chip (not just positive / negative, which would be simpler), and in a just-posted Nature Medicine paper it shows that the signal vs. concentration curve goes 1000x farther on the low end (and the high end too, i.e. more dynamic range) before blending in with the background than the same assay (and antibodies) used on ELISA. Plus, it is a simple device that performs identically in saliva, urine, different pH and temperatures, and which is generally rugged and not too picky about the experimental conditions. This is quite helpful too.
Another point of the publication is that this device can measure small but slowly increasing tumor marker concentrations in lab mice which are known to have cancer. The key is that these tumor markers can be measured with this chip, but are too small in concentration for the traditional platforms such as ELISA. This means you can (in mice, at least) get important early cancer growth trend information (from a blood test) which you probably wouldn't have been able to obtain before.
Just published in Nature Medicine Advanced Online publications (unfortunately requires subscription):
http://www.nature.com/nm/journal/vaop/ncurrent/abs/nm.2032.html [nature.com]
Technical Report abstract
Nature Medicine
Published online: 11 October 2009 | doi:10.1038/nm.2032
Matrix-insensitive protein assays push the limits of biosensors in medicine